A conventional screw is formed with threaded cylindrical rod engageable with a similarly threaded cylindrical hole formed in a wall or an article to be fastened by the screw. The threaded cylindrical hole should be pre-drilled by a drill tool so that the screw can be engaged with the threaded hole for fastening the screw in the hole for fastening or fixing purpose. However, such a conventional screw still has the following drawbacks:
1. A tool of drill must be provided for drilling the female threaded hole for plugging in the screw as driven by another tool such as a driver to cause operating inconvenience.
2. If the threaded hole is not made precisely to be engageable with the screw threads, the screw fixed in the threaded hole may be loosened or easily released from the hole, influencing its fastening effect.
The present inventor has found the defects of a conventional screw and invented the present screw coexistent with a drill.